1. Dr. Alessandra Bigongiari
Experienced Researcher
At starting date: 1st May 2013
Consolidation of experimental, analytical and numerical results for laminar and turbulent combustor
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

2. Background 2002-2007 University of Pisa : 2007-2008
Msc
Plasma
Physics
University of Pisa :
Physics of materials
Queen's University : MSc Plasma Physics
2008
TEA sistemi :
Validation with experimental data of models for two-phase flow
Ecole Polytechnique: (Paris)
PhD :Surface Waves in Laser-Plasma Interaction
→ 2013
Short post-doc
(6 months)
PhD
Surface Waves in
Laser-Plasma
Interaction
BSc & Msc
Physics of Materials
Before joining the project, I have been studying in different university in Europe. I graduated at University of Pisa, I have a master degree from Queen’s University and I did my PhD at École Polytechnique. I have also participated to a short research project at a private company.
TEA sistemi s.p.a.
Research project
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

3. Role in the project
ER –
Consolidation of experimental, analytical and numerical results for laminar and turbulent combustor
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

4. Research activity
Analysis of Thermo-acoustic instabilities with the Green function approach
Analytical Approach:
Model for the burner:
The Green function is the velocity potential created by an impulsive point source
Green function
Velocity potential
Acoustic Velocity
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

5. Ωm Analytical Approach:
Modal analysis (presented at the ICSV conference , Beijing, China)
Heat release rate: linear dependence on the delayed acoustic velocity
Decomposition of the Green function and acoustic velocity as a sum of modes
The integral equation can be studied using modal analysis. Assuming a linear heat release rate we can decompose the Green function and the acoustic velocity into modes. This allow the calculation of the heat driven frequencies, that is the resonant frequencies of the duct when an heat source is present.
The importance of this result is that, while the natural frequencies depend on the pipe characteristic only, the heat driven frequencies depend on the characteristic of the source
Depends on :
the delay τ
the natural frequencies ωn
The heater power K
The number of modes Ωm
heat driven frequency
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

6. Numerical iteration: the integral equation is discretized
Numerical approach:
Numerical iteration: the integral equation is discretized
Time evolution of the perturbation
Perturbed q (t)
Perturbed u(t)
Perturbed u(t-τ)
Perturbed q (t+τ)
The integral equation can also be used to obtain the temporal evolution of the perturbation through numerical iteration.
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

7. Comparison with numerical, analytical and experimental work at IIT Madras
Comparison with modal analysis based on Galerkin expansion.
Comparison with numerical iteration based on Galerkin expansion.
Visit of the laboratory: comparison with experimental data (pressure time series, flame images).
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

8. Work in progress
New model: Dependence of the time lag on the perturbation amplitude
stable
unstable
At present I am working on a new model for the heat release rate, which is able to predict hysteresis in the system. This involves the dependence on the actual perturbation and the delayed effects of perturbation at a time t-tau. The coefficients in the formula are under investigation. At the same time the time lag tau will have a constant component and a component which depend on the perturbation amplitude.
The stability map shows Hysteresis when the pipe length is varied
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

9. TANGO workshops attended Training sessions at host institution
n3l Summer School and Workshop (June 2013)
1st Workshop on Communication and Outreach (September 2013)
Workshop on Experimental Methods in Thermoacoustics (February 2014)
Workshop on Aeroacoustics in Confined Flows of Low Mach Number (May 2014)
Workshop on Gender Issues (May 2014)
Training sessions at host institution
Workshop on the Countdown to Horizon 2020
Information Day on Marie Sklodowska Curie Individual Fellowships
Conferences attended
Marie Curie Action: On the last lap to Horizon 2020 (Florence, Italy, November 2013
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

10. Dissemination and Outreach
Conferences
21st International Congress on Sound and Vibration, Beijing, China, July 2014
Publications
A. Bigongiari and M.A Heckl (2014) "Coupling of heat-driven modes in the Rijke tube", Proceedings, of the 21st International Congress on Sound and Vibration, July 2014, Beijing, China.
TANGO Science Market c
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK

11. Secondment and career plans
Secondment at Ansaldo Energia, February – March Consolidation of numerical and analytical combustor models :
Effects of fuel molar fraction
Mean flow
Career plans
Research in applied physics, based at research institute or company
Dr. A. Bigongiari (ER) / TANGO Mid-Term Review meeting, Sept. Keele, UK